The combination of these five simple forms of inference gives rise to the composite forms of inference, [240] all of which may be again resolved into their simple forms. [241] Among composite forms of inference, those composed of similar parts are distinguished from those composed of dissimilar parts; [242] in the treatment of the former, however, such a useless formality is displayed, that it is hard to say what meaning the Stoics attached to them. [243] If two or more inferences, the conclusion of one of which is the first premiss of the other, are so combined that the judgment which constitutes the conclusion and premiss at once is omitted in each case, the result is a Sorites or Chain-inference. The rules prescribed by the Peripatetics for the Chain-inference are developed by the Stoics with a minuteness far transcending all the requirements of science. [244] With these [(δ) Inference from a single premiss.] composite forms of inference Antipater contrasted other forms having only a single premiss, [245] but it was an addition to the field of logic of very doubtful worth. On a few other points connected with the Stoic theory of illation, we have very imperfect information. [246] The loss, however, is not to be regretted, seeing that in what we already possess there is conclusive evidence that the objections brought against the Stoic logic were really well deserved, because of the microscopic care expended by them on the most worthless logical forms. [247] [(c) Refutation of fallacies.] Next to describing inferences which are valid, another subject engaged the close attention of the Stoics, and afforded opportunity for displaying their dialectical subtlety. This is the enumeration and refutation of false inferences, [248] and in particular the exposing of the many fallacies which had become current since the age of the Sophists and Megarians. In this department, as might be expected, Chrysippus led the way. [249] Not that Chrysippus was always able to overcome the difficulties that arose; witness his remarkable attitude towards the Chain-inference, from which he thought to escape by withholding judgment. [250] The fallacies, however, to which the Stoics devoted their attention, and the way in which they met them, need not occupy our attention further. [251] [D. Estimate of Stoic Logic.] [(1) Its shortcomings.]